Composite material and preparation method thereof, positive pole piece, secondary battery and electric device

Abstract

The invention discloses a composite material and a preparation method thereof, a positive pole piece, a secondary battery and an electric device, and belongs to the technical field of batteries. The composite material comprises a lithium-containing compound, a catalyst and a conductive agent, and the lithium-containing compound comprises a lithium element, a carbon element and an oxygen element; the catalyst comprises one or more of transition metal oxides, transition metal carbides, transition metal nitrides or transition metal phosphides; the total pore volume V of the composite material is more than or equal to 0.02 cm < 3 > / g and less than or equal to 1cm < 3 > / g, and the average pore size D of the composite material is more than or equal to 2nm and less than or equal to 50nm. According to the technical scheme, the capacity of the battery can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a composite material, a preparation method thereof, a positive electrode sheet, a secondary battery, and an electrical device. Background Art

[0002] With the increasing environmental pollution, the new energy industry has attracted more and more attention. In the new energy industry, battery technology is an important factor related to its development.

[0003] The development of battery technology needs to consider various design factors, such as capacity, energy density, cycle life, reliability, etc. During the first charge and discharge process of a battery cell, a solid electrolyte interface (SEI) film is formed on the surface of the negative electrode. The existence of the SEI film will consume a large amount of lithium ions, affecting the capacity of the battery. Therefore, how to provide a composite material to supplement more lithium ions, thereby improving the capacity of the battery is a technical problem to be solved urgently. Summary of the Invention

[0004] The present application is made in view of the above problems, and its purpose is to provide a composite material to improve the capacity of the battery.

[0005] To achieve the above purpose, the present application provides a composite material, a preparation method thereof, a positive electrode sheet, a secondary battery, and an electrical device.

[0006] In a first aspect, a composite material is provided, including: a lithium-containing compound, a catalyst, and a conductive agent, wherein the lithium-containing compound includes lithium element, carbon element, and oxygen element; the catalyst includes one or more of an oxide of a transition metal, a carbide of a transition metal, a nitride of a transition metal, or a phosphide of a transition metal; the total pore volume V of the composite material satisfies: 0.02 cm 3 / g ≤ V ≤ 1 cm 3 / g, and the average pore diameter D of the composite material satisfies: 2 nm ≤ D ≤ 50 nm.

[0007] In the embodiments of the present application, the lithium-containing compound can decompose to generate lithium ions, so as to supplement lithium ions to the battery; the catalyst can catalyze the decomposition of the lithium-containing compound, so that the lithium-containing compound decomposes more easily, thereby providing more lithium ions to the battery. The total pore volume V of the composite material satisfies: 0.02 cm 3 / g ≤ V ≤ 1 cm 3 / g, the average pore diameter D of the composite material satisfies: 2 nm ≤ D ≤ 50 nm. In this way, the composite material has more pores, so the density of the composite material is lower, the specific surface area of the composite material is larger, the contact area between the electrolyte and the lithium-containing compound is larger, which helps the diffusion of lithium ions, and thus is beneficial to improving the capacity of the battery. Therefore, the technical solution of the embodiment of the present application can improve the capacity of the battery.

[0008] In a possible implementation manner, the total pore volume V of the composite material satisfies: 0.1 cm 3 / g ≤ V ≤ 0.5 cm 3 / g, and the average pore diameter D of the composite material satisfies: 5 nm ≤ V ≤ 20 nm. In this way, the composite material can have a larger specific surface area, the contact area between the electrolyte and the lithium-containing compound is larger, which helps the diffusion of lithium ions, and thus is beneficial to improving the capacity of the battery.

[0009] In a possible implementation manner, the morphology of the lithium-containing compound is primary particles, and / or the morphology of the composite material is secondary particles.

[0010] The morphology of the lithium-containing compound is primary particles. The lithium-containing compound, the conductive agent and the catalyst are mixed together to form a composite material with the morphology of secondary particles. The morphology of the lithium-containing compound being primary particles is beneficial, on the one hand, to the full contact between the lithium-containing compound and the catalyst to achieve a better catalytic effect, thereby being beneficial to reducing the decomposition voltage of the lithium-containing compound and improving the capacity of the battery; on the other hand, the conductive agent is dispersed around the primary particle lithium-containing compound, which is beneficial to improving the electronic conductivity of the lithium-containing compound, and thus is beneficial to improving the capacity of the battery.

[0011] In a possible implementation manner, the specific surface area S of the composite material satisfies: 10 m 2 / g ≤ S ≤ 150 m 2 / g; optionally, 30 m 2 / g ≤ S ≤ 100 m 2 / g.

[0012] When the specific surface area S of the composite material is not less than 10 m 2 / g, the contact area between the lithium-containing compound and the electrolyte is more appropriate, which is beneficial to the full contact between the lithium-containing compound and the electrolyte and the decomposition of the lithium-containing compound; when the specific surface area S of the composite material does not exceed 150 m 2 / g, the risk that the pores in the composite material absorb moisture in the environment and cause the water content of the composite material to be too high and block the pores can be reduced, thereby reducing the influence on the decomposition of the lithium-containing compound.

[0013] In a possible implementation, the sphericity of the particles of the composite material is 0.9 to 1. In this way, the composite material has a spherical or nearly spherical morphology.

[0014] In a possible implementation, the chemical formula of the lithium-containing compound is Li2C x O y , where 1 ≤ x ≤ 4 and 3 ≤ y ≤ 6. Optionally, the lithium-containing compound includes one or more of Li2C2O4, Li2CO3, Li2C4O4, Li2C3O5, or Li2C4O6. Under the action of voltage and a catalyst, the above lithium-containing compound can decompose into lithium ions and gases (such as carbon monoxide, carbon dioxide). The lithium ions generated by decomposition can play a role in supplementing lithium ions, which is beneficial to improving the capacity of the battery; the gases generated by decomposition will not remain in the positive electrode sheet and will not affect the long-term reliability and other performance of the battery monomer due to the residues generated by decomposition. In addition, the above lithium-containing compound has good stability and can stably exist in air and organic solvents, and can be compatible with the coating process of the positive electrode slurry.

[0015] In a possible implementation, the chemical formula of the oxide of the transition metal is M α O β , where 0 < α ≤ 3 and 0 < β ≤ 5, and M includes one or more of Ni, Co, Fe, Mn, V, Cr, Cu, or Ti; optionally, M α O β includes one or more of NiO, Co3O4, Fe2O3, MoO3, or V2O5. The above catalyst can reduce the decomposition voltage of the lithium-containing compound and cause the lithium-containing compound to decompose at a lower voltage.

[0016] In a possible implementation, the transition metal carbides include one or more of molybdenum carbide, vanadium carbide, tungsten carbide, titanium carbide, cobalt carbide, iron carbide, or nickel carbide; and / or, the transition metal nitrides include one or more of molybdenum nitride, vanadium nitride, titanium nitride, manganese nitride, cobalt nitride, iron nitride, or nickel nitride; and / or, the transition metal phosphides include one or more of nickel phosphide, cobalt phosphide, manganese phosphide, tungsten phosphide, or molybdenum phosphide. The above transition metal carbides, transition metal nitrides, and transition metal phosphides have good catalytic effects and can catalyze the decomposition of the lithium-containing compound.

[0017] In a possible implementation, the conductive agent includes a carbon material; optionally, the conductive agent includes a carbon-based conductive agent; optionally, the carbon material includes one or more of carbon nanotubes, carbon fibers, acetylene black, Ketjen black, conductive carbon black, C60, or graphene. The carbon material has good electrical conductivity and can be well compatible with other materials in the battery; the composite material includes the carbon material, which is beneficial to reducing the resistivity of the composite material, improving the electrical conductivity of the composite material, and increasing the capacity of the battery.

[0018] In a possible implementation, the volume average particle size Dv501 of the lithium-containing compound satisfies: 50 nm ≤ Dv501 ≤ 500 nm; optionally, 100 nm ≤ Dv501 ≤ 300 nm.

[0019] When the volume average particle size Dv501 of the lithium-containing compound is not less than 50 nm, it is convenient to prepare a composite material with multiple channels penetrating the composite material, and the risk of primary particle agglomeration can also be reduced; when the volume average particle size Dv501 of the lithium-containing compound does not exceed 500 nm, it is beneficial for the lithium-containing compound of the primary particles to contact the catalyst, thereby facilitating the decomposition of the lithium-containing compound. In summary, by setting 50 nm ≤ Dv501 ≤ 500 nm, the battery cell has a high capacity.

[0020] In a possible implementation, the volume average particle size Dv502 of the composite material satisfies: 1 μm ≤ Dv502 ≤ 15 μm; optionally, 2 μm ≤ Dv502 ≤ 10 μm.

[0021] When the volume average particle size Dv502 of the composite material is not less than 1 μm, the risk of composite material agglomeration can be reduced; when the volume average particle size Dv502 of the composite material does not exceed 15 μm, the composite material has a suitable particle size, the lithium ions released from the lithium-containing compound have a suitable diffusion distance, which is beneficial for the lithium ions to have a high transmission rate and for more lithium ions to be released, thereby facilitating the improvement of the battery capacity.

[0022] In a possible implementation, based on the total mass of the composite material, the mass content A of the conductive agent satisfies: 1 wt% ≤ A ≤ 40 wt%; optionally, A satisfies: 2 wt% ≤ A ≤ 20 wt%.

[0023] When the mass content A of the conductive agent is not less than 1 wt%, the composite material has high electrical conductivity and low resistivity; when the mass content A of the conductive agent does not exceed 40 wt%, the conductive agent has a suitable mass ratio, and the catalyst and the lithium-containing compound also have suitable mass ratios, and the battery cell has a suitable capacity.

[0024] In a possible implementation, based on the total mass of the composite material, the mass content B of the catalyst satisfies: 0.5 wt% ≤ B ≤ 20 wt%; optionally, B satisfies: 1 wt% ≤ B ≤ 10 wt%.

[0025] When the mass content B of the catalyst is not less than 0.5 wt%, the contact area between the catalyst and the lithium-containing compound is appropriate, and it has a good catalytic effect, which is conducive to catalyzing the decomposition of the lithium-containing compound and improving the capacity of the battery; when the mass content B of the catalyst does not exceed 20 wt%, it is conducive to adding more lithium-containing compounds to the composite material and improving the capacity of the battery.

[0026] In a second aspect, a method for preparing a composite material is provided, including: adding a lithium source, a catalyst, a conductive agent, and a pore-forming agent into a solvent to obtain a slurry, which is one or more of transition metal oxides, transition metal carbides, transition metal nitrides, or transition metal phosphides; drying the slurry to obtain dried powder; washing the dried powder to obtain the composite material. The composite material prepared by this method has a high specific surface area, which is conducive to improving the capacity of the battery electrode body.

[0027] In a possible implementation, the pore-forming agent includes: one or more of oxalic acid, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, or polyacrylic acid. The above-mentioned pore-forming agents are easily soluble in water and absolute ethanol. By selecting the above-mentioned pore-forming agents, it is convenient to prepare the composite material.

[0028] In a possible implementation, the drying the slurry to obtain dried powder includes: drying the slurry by spray drying to obtain dried powder. By selecting the spray drying method, the drying is relatively rapid, and the slurry can be directly dried into powder.

[0029] In a possible implementation, the feeding rate V of the slurry satisfies: 20 mL / min ≤ V ≤ 100 mL / min; optionally, 45 mL / min ≤ V ≤ 85 mL / min. The feeding rate of the slurry affects the size of the primary particles. By selecting the feeding rate within the above range, it is conducive to obtaining primary particles of lithium-containing compounds with a more appropriate particle size.

[0030] In a possible implementation, the temperature T of the drying treatment satisfies: 150 °C ≤ T ≤ 250 °C; optionally, 175 °C ≤ T ≤ 225 °C. The temperature of the drying treatment affects the growth and nucleation process of the secondary particles of the composite material. By selecting the temperature within the above range, it is conducive to obtaining secondary particles of the composite material with a suitable particle size.

[0031] In a possible implementation, based on the sum of the masses of the lithium source, the catalyst, the conductive agent, and the pore-forming agent, the mass content C of the pore-forming agent satisfies: 1 wt% ≤ C ≤ 5 wt%; optionally, 2 wt% ≤ C ≤ 4 wt%. The mass content of the pore-forming agent affects the specific surface area of the composite material. By selecting the mass content within the above range, it is beneficial to obtain a composite material with a suitable specific surface area.

[0032] In a possible implementation, the lithium source includes one or more of Li2C2O4, Li2CO3, Li2C4O4, Li2C3O5, Li2C4O6, or LiOH. The lithium source can be dissolved in a solvent and can provide lithium ions, thereby obtaining a slurry containing lithium ions, which facilitates the preparation of the composite material through the slurry.

[0033] In a possible implementation, removing the pore-forming agent from the dried powder through washing treatment to obtain the composite material includes: adding the dried powder into absolute ethanol, and removing the pore-forming agent through washing and filtration to obtain the composite material. The pore-forming agent can be dissolved in absolute ethanol. By washing and filtering the dried powder with absolute ethanol, the pore-forming agent in the dried powder can be removed; after drying, a composite material with a porous structure and a large specific surface area can be obtained.

[0034] In a third aspect, a positive electrode sheet is provided, including a positive electrode active material; the composite material in the first aspect and any one of its possible implementations, and / or the composite material prepared by the method in the second aspect and any one of its possible implementations.

[0035] In a fourth aspect, a secondary battery is provided, including the positive electrode sheet in the third aspect and any one of its possible implementations.

[0036] In a possible implementation, the secondary battery is a secondary battery before formation.

[0037] In a fifth aspect, an electrical device is provided, including the secondary battery described in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0039] Figure 1 Schematic diagram of the composite material preparation method in an embodiment of the present application;

[0040] Figure 2 Schematic diagram of a battery cell according to an embodiment of the present application;

[0041] Figure 3 Schematic diagram of a battery according to an embodiment of the present application;

[0042] Figure 4 Schematic diagram of an electrical device according to an embodiment of the present application;

[0043] Figure 5 SEM schematic diagram of a composite material according to an embodiment of the present application;

[0044] Figure 6 Partially enlarged SEM schematic diagram of a composite material according to an embodiment of the present application;

[0045] Figure 7 EDS schematic diagram of a composite material according to an embodiment of the present application;

[0046] Figure 8 SEM schematic diagram of a composite material of a comparative example of the present application;

[0047] Figure 9 Partially enlarged SEM schematic diagram of a composite material of a comparative example of the present application. Detailed description of specific embodiments

[0048] The embodiments of the composite material, its preparation method, the positive electrode sheet, the secondary battery, and the electrical device of the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary details are omitted. For example, there are cases where the detailed description of well-known matters and the repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0049] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In this application, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0051] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.

[0052] If there is no special instruction, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0053] The development of battery technology needs to consider various design factors, such as capacity, energy density, cycle life, reliability, etc. During the first charge and discharge process of a battery cell, a solid electrolyte interphase (SEI) film is formed on the surface of the negative electrode. The presence of the SEI film consumes a large amount of lithium ions, affecting the capacity of the battery. To increase the capacity of the battery, a lithium-containing compound with a relatively high lithium content is added to the positive electrode slurry. For example, lithium oxalate is added to provide more lithium ions to the battery cell. However, for lithium-containing compounds such as lithium oxalate, their decomposition voltage is relatively high and usually requires cooperation with a catalyst to reduce the decomposition voltage of the lithium-containing compound, thereby providing active lithium ions to increase the capacity of the battery. However, this treatment method still has a relatively small improvement in the capacity of the battery at present.

[0054] In view of this, an embodiment of the present application provides a composite material, including a lithium-containing compound, a catalyst, and a conductive agent. The composite material is a composite material with a porous morphology. The total pore volume and average pore diameter of the composite material are within a certain range, and this composite material can increase the capacity of the battery.

[0055] The composite material in the embodiment of the present application can be used as a lithium supplement agent, that is, it can supplement the lithium ions consumed by the negative electrode. As an example, this composite material can be mixed with a positive electrode active material (such as lithium iron phosphate, ternary material, etc.) and then prepared into a positive electrode slurry for use.

[0056] The secondary battery in the embodiment of the present application can refer to a battery cell or a battery pack. A battery cell can be the smallest unit of a battery pack. A battery cell includes a positive electrode plate, a negative electrode plate, a separator, an electrolyte, etc.

[0057] During the charging process of a lithium-ion secondary battery, lithium ions are removed from the positive electrode active material, move and embed into the negative electrode material; during the discharging process, lithium ions are removed from the negative electrode material, move and embed into the positive electrode active material.

[0058] It should be understood that the "embedding" process described in the present application refers to the process in which lithium ions are embedded in the positive electrode active material and the negative electrode material due to an electrochemical reaction. The "removal" and "deintercalation" processes described in the present application refer to the process in which lithium ions are removed from the positive electrode active material and the negative electrode material due to an electrochemical reaction.

[0059] [Composite Material]

[0060] An embodiment of the present application provides a composite material, which includes a lithium-containing compound, a catalyst, and a conductive agent.

[0061] The lithium-containing compound includes lithium, carbon, and oxygen elements. The lithium-containing compound can include an organic lithium-containing compound, such as Li2C2O4, or an inorganic lithium-containing compound, such as Li2CO3.

[0062] Lithium-containing compounds can decompose under the action of voltage into lithium ions and carbon oxides (such as CO, CO2). The lithium ions generated by the decomposition can supplement lithium ions to the battery, thereby facilitating the improvement of the battery capacity.

[0063] The catalyst includes one or more of transition metal oxides, transition metal carbides, transition metal nitrides, or transition metal phosphides. The catalyst can reduce the decomposition voltage of the lithium-containing compound.

[0064] Transition metal carbides, transition metal nitrides, and transition metal phosphides can be obtained by treating transition metal oxides. The transition metal carbide can be molybdenum carbide, tungsten carbide, the transition metal nitride can be molybdenum nitride, manganese nitride. The transition metal phosphide can be nickel phosphide, cobalt phosphide, manganese phosphide, tungsten phosphide, or molybdenum phosphide.

[0065] Transition metal oxides, transition metal carbides, transition metal nitrides, and transition metal phosphides not only have high conductivity, but also have abundant surface active sites and a relatively high specific surface area, and can catalyze the decomposition of lithium-containing compounds.

[0066] Transition metal oxides, transition metal carbides, transition metal nitrides, and transition metal phosphides can catalyze the decomposition of lithium-containing compounds under the action of voltage, that is, they can reduce the decomposition voltage of lithium-containing compounds.

[0067] As an example, the catalyst is a transition metal oxide, such as Ni x O, where 0.67 ≤ x ≤ 1. The embodiments of the present application include but are not limited to this, as long as it can catalyze the decomposition of lithium-containing compounds.

[0068] The conductive agent is a material that can conduct electricity. For example, the conductive agent can be a carbon material.

[0069] In the composite material, the lithium-containing compound is in contact with the catalyst and the conductive agent. In this way, the catalyst can catalyze the decomposition of the lithium-containing compound, and the conductive agent is conducive to the realization of electron transfer, thereby facilitating the reduction of the decomposition voltage of the composite material and the exertion of the capacity of the composite material.

[0070] The total pore volume V of the composite material satisfies: 0.02 cm 3 / g ≤ V ≤ 1 cm 3 / g, and the average pore diameter D of the composite material satisfies: 2 nm ≤ D ≤ 50 nm.

[0071] The total pore volume V and the average pore diameter D can be obtained by gas adsorption measurement.

[0072] V can be 0.02 cm 3 / g, 0.1 cm3 / g, 0.3 cm 3 / g, 0.5 cm 3 / g, 1 cm 3 / g or any value within the above range, D can be 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm or any value within the above range.

[0073] The total pore volume can refer to the volume of all pores in the composite material. The average pore diameter can refer to the average size of all pores in the composite material.

[0074] The composite material can have a porous morphology, and the total pore volume V and the average pore diameter D of the composite material satisfy the above range. In this way, there are more pores and channels in the composite material.

[0075] The channels can serve as channels for lithium ion transport and penetrate the composite material, and the electrolyte can infiltrate the channels.

[0076] There are more channels in the composite material and the channels are relatively evenly distributed. The composite material is a material with a porous structure and has a large specific surface area. The composite material has a large specific surface area, so that the contact area between the electrolyte and the lithium-containing compound increases, which is beneficial to the transport and diffusion of lithium ions during the charging process of the battery cell, and is beneficial to the extraction of more lithium ions from the composite material, thus being beneficial to improving the capacity of the battery.

[0077] In the embodiments of the present application, the lithium-containing compound can decompose to generate lithium ions and gas, so as to supplement lithium ions to the battery; the catalyst can catalyze the decomposition of the lithium-containing compound, so that the lithium-containing compound decomposes more easily, thereby providing more lithium ions to the battery. The total pore volume V of the composite material satisfies: 0.02 cm 3 / g ≤ V ≤ 1 cm 3 / g, the average pore diameter D of the composite material satisfies: 2 nm ≤ D ≤ 50 nm. In this way, the composite material has more channels, so that the density of the composite material is lower, the composite material has a large specific surface area, the contact area between the electrolyte and the lithium-containing compound is large, which helps the diffusion of lithium ions, and thus is beneficial to improving the capacity of the battery. Therefore, the technical solution of the embodiments of the present application can improve the capacity of the battery.

[0078] In some embodiments, the total pore volume V of the composite material satisfies: 0.1 cm 3 / g ≤ V ≤ 0.5 cm 3 / g, the average pore diameter D of the composite material satisfies: 5 nm ≤ D ≤ 20 nm. In this way, the composite material can have a larger specific surface area, the contact area between the electrolyte and the lithium-containing compound is large, which helps the diffusion of lithium ions, and thus is beneficial to improving the capacity of the battery.

[0079] In some embodiments, the morphology of the lithium-containing compound is primary particles, and / or the morphology of the composite material is secondary particles.

[0080] The morphology of the lithium-containing compound is primary particles. The lithium-containing compound, the conductive agent, and the catalyst are mixed together to form a composite material with the morphology of secondary particles.

[0081] Primary particles may refer to unagglomerated particles, and secondary particles may refer to particles formed by the agglomeration of primary particles.

[0082] The shape of the primary particles can be irregular. For example, the primary particles can be spherical or various other irregular shapes.

[0083] The composite material can be spherical or nearly spherical particles. The lithium-containing compound, the conductive agent, and the catalyst of the primary particles are mixed to form a spherical or nearly spherical composite material. In this way, after the lithium-containing compound decomposes, the conductive agent and the catalyst in the composite material can retain the three-dimensional structure of the composite material, and the holes or vacancies formed at the original positions of the lithium-containing compound will not be directly reflected on the positive electrode sheet. Therefore, the risk of damage to the conductive network of the positive electrode sheet is reduced, and the impact on the transport of electrons and ions in the positive electrode sheet is small, thereby improving the capacity of the battery. In addition, after the lithium-containing compound decomposes, vacancies or holes are left in the composite material. These vacancies can enhance the infiltration of the electrolyte, and the electrolyte on the vacancies can provide channels for ion transport, which is beneficial to the transport of ions (such as lithium ions), thus improving the capacity of the battery.

[0084] The morphology of the lithium-containing compound being primary particles is beneficial in two aspects. On the one hand, it is conducive to the full contact between the lithium-containing compound and the catalyst to achieve a better catalytic effect, thereby reducing the decomposition voltage of the lithium-containing compound. On the other hand, the conductive agent is dispersed around the lithium-containing compound of the primary particles, which is beneficial to improving the electronic conductivity of the lithium-containing compound, thereby improving the capacity of the battery.

[0085] In some embodiments, the specific surface area S of the composite material satisfies: 10m 2 / g ≤ S ≤ 150m 2 / g.

[0086] S can be 10m 2 / g, 20m 2 / g, 30m 2 / g, 80m 2 / g, 100m 2 / g, 150m 2 / g or any value within the above range.

[0087] When the specific surface area S of the composite material is not less than 10m 2In the case of / g, the lithium-containing compound has more pores, which is conducive to the full contact between the lithium-containing compound and the electrolyte, and thus conducive to the decomposition of the lithium-containing compound; when the specific surface area S of the composite material does not exceed 150 m 2 / g, it is possible to reduce the risk that the pores in the composite material absorb moisture in the environment, resulting in a high water content in the composite material that blocks the pores, thereby reducing the impact on the decomposition of the lithium-containing compound.

[0088] For example, during the storage of the composite material and the process of using the composite material to prepare battery monomers, the pores in the composite material can absorb moisture in the external environment. By setting the specific surface area of the composite material to be less than or equal to 150 m 2 / g, the risk that the pores of the composite material introduced into the prepared battery monomers are blocked can be reduced. Thus, the composite material has better performance, and the capacity of the battery monomers can also be effectively improved.

[0089] Optionally, 30 m 2 / g ≤ S ≤ 100 m 2 / g. In this way, the battery monomers can have higher capacity.

[0090] In some embodiments, the chemical formula of the lithium-containing compound is Li2C x O y , where 1 ≤ x ≤ 4 and 3 ≤ y ≤ 6.

[0091] For the chemical formula Li2C x O y , x and y satisfy the following relationship: x + y = 2n, where 2 ≤ n ≤ 5.

[0092] Among them, x can be 1, 2, 3, 4 or any value within the above range, y can be 3, 4, 5, 6 or any value within the above range, and n can be 2, 3, 4, 5 or any value within the above range. As an example, x, y, and n are all positive integers.

[0093] Under the action of voltage and catalyst, the above lithium-containing compound can decompose into lithium ions and gases (such as carbon monoxide, carbon dioxide). The decomposed lithium ions can play a role in supplementing lithium ions, which is conducive to improving the capacity of the battery; the decomposed gases will not remain in the positive electrode plate, and will not affect the long-term reliability and other performance of the battery monomers due to the residues generated by decomposition. In addition, the above lithium-containing compound has good stability, can stably exist in air and organic solvents, and can be compatible with the coating process of the positive electrode slurry.

[0094] As an example, the gases generated by the decomposition of the lithium-containing compound can be sucked out of the battery monomers through tools such as suction nozzles during the formation step.

[0095] In some embodiments, the lithium-containing compound includes one or more of Li2C2O4, Li2CO3, Li2C4O4, Li2C3O5 or Li2C4O6. The above lithium-containing compounds are relatively easy to obtain and are convenient to be applied in the composite material.

[0096] In some embodiments, the chemical formula of the transition metal oxide is M α O β , where 0 < α ≤ 3, 0 < β ≤ 5, and M includes one or more of Ni, Co, Fe, Mn, V, Cr, Cu or Ti.

[0097] α can be 0.5, 1, 2, 3 or any value within the above range, and β can be 0.5, 1, 2, 3, 4, 5 or any value within the above range. In some examples, α and β are positive integers.

[0098] The above catalyst can reduce the decomposition voltage of the lithium-containing compound and enable the lithium-containing compound to decompose at a lower voltage.

[0099] In some embodiments, M α O β includes one or more of NiO, Co3O4, Fe2O3, MoO3 or V2O5. The above catalyst is relatively easy to obtain and is convenient to be applied in the composite material.

[0100] In some embodiments, the transition metal carbide includes one or more of molybdenum carbide, vanadium carbide, tungsten carbide, titanium carbide, cobalt carbide, iron carbide or nickel carbide; and / or, the transition metal nitride includes one or more of molybdenum nitride, vanadium nitride, titanium nitride, manganese nitride, cobalt nitride, iron nitride or nickel nitride; and / or, the transition metal phosphide includes one or more of nickel phosphide, cobalt phosphide, manganese phosphide, tungsten phosphide or molybdenum phosphide. The above transition metal carbides, transition metal nitrides and transition metal phosphides have good catalytic effects and can catalyze the decomposition of the lithium-containing compound.

[0101] In some embodiments, the conductive agent includes a carbon material.

[0102] Optionally, the conductive agent includes a carbon-based conductive agent. For example, the conductive agent includes a carbon-based material. For example, the conductive agent can be conductive graphite, conductive carbon black, graphene, etc.

[0103] Optionally, the carbon material includes one or more of carbon nanotubes, carbon fibers, acetylene black, Ketjen black, conductive carbon black, C60 or graphene.

[0104] Carbon materials have good electrical conductivity and can be well compatible with other materials in the battery. The composite material includes carbon materials, which is beneficial to reducing the resistivity of the composite material, improving the electrical conductivity of the composite material, and increasing the capacity of the battery.

[0105] Optionally, the carbon material is a zero-dimensional carbon material. For example, the carbon material is fullerene.

[0106] In some embodiments, the volume average particle size Dv501 of the lithium-containing compound satisfies: 50 nm ≤ Dv501 ≤ 500 nm.

[0107] Dv501 can be 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 300 nm, 500 nm, or any value within the above range.

[0108] Dv50 can refer to the particle size corresponding to when the cumulative particle size volume distribution number of a sample reaches 50%, which can mean that the particles smaller than it account for 50%. Here, Dv501 is used to distinguish from Dv502 below, representing the volume average particle size of different substances.

[0109] The particle size of the lithium-containing compound is in the nanometer range. In this way, during the decomposition process of the lithium-containing compound, the lithium-containing compound can decompose faster. Compared with lithium-containing compounds with larger particle sizes (for example, micron-sized), the setting of the lithium-containing compound in this embodiment can reduce the risk that the particle part of the lithium-containing compound decomposes and the lithium-containing compound does not contact the catalyst.

[0110] When the volume average particle size Dv501 of the lithium-containing compound is not less than 50 nm, it is convenient to prepare a composite material with multiple through-holes in the composite material, and the risk of primary particle agglomeration can also be reduced; when the volume average particle size Dv501 of the lithium-containing compound does not exceed 500 nm, it is beneficial for the primary particle lithium-containing compound to contact the catalyst, thus facilitating the decomposition of the lithium-containing compound. In summary, by setting 50 nm ≤ Dv501 ≤ 500 nm, the battery monomer has a higher capacity.

[0111] Optionally, 100 nm ≤ Dv501 ≤ 300 nm. In this way, the battery monomer has a higher capacity.

[0112] Since the lithium-containing compound is a primary particle and the volume average particle size of the lithium-containing compound is in the nanometer range, there are almost no closed pores inside the composite material, and the total pore volume of the composite material can be considered as the total pore volume of the through-holes (i.e., the holes passing through the composite material). In addition, the pores in the composite material are basically mesopores.

[0113] In some embodiments, the volume average particle size Dv502 of the composite material satisfies: 1 μm ≤ Dv502 ≤ 15 μm.

[0114] Dv502 can be 1μm, 2μm, 5μm, 10μm, 12μm, 15μm or any value within the above range.

[0115] When the volume average particle size Dv502 of the composite material is not less than 1μm, the risk of agglomeration of the composite material can be reduced; when the volume average particle size Dv502 of the composite material does not exceed 15μm, the composite material has a suitable particle size, and the lithium ions released from the lithium-containing compound have a suitable diffusion distance, which is beneficial to enabling the lithium ions to have a high transmission rate, thereby being beneficial to enabling the battery cell to have suitable kinetic performance.

[0116] Optionally, 2μm ≤ Dv502 ≤ 10μm. In this way, the battery cell has a higher capacity.

[0117] It should be noted that both Dv501 and Dv502 in the embodiments of the present application represent the volume average particle size of the material, where the "1" in Dv501 and the "2" in Dv502 are used to distinguish the volume average particle sizes of different substances.

[0118] In some embodiments, based on the total mass of the composite material, the mass content A of the conductive agent satisfies: 1wt% ≤ A ≤ 40wt%.

[0119] A can be 1wt%, 10wt%, 15wt%, 25wt%, 30wt%, 35wt%, 40wt% or any value within the above range.

[0120] When the mass content A of the conductive agent is not less than 1wt%, the composite material has high conductivity and low resistivity, which is beneficial to improving the capacity of the battery; when the mass content A of the conductive agent does not exceed 40wt%, the conductive agent has a suitable mass ratio, and the catalyst and the lithium-containing compound also have suitable mass ratios, which is beneficial to improving the capacity of the battery.

[0121] In this embodiment, by setting A to satisfy 1wt% ≤ A ≤ 40wt%, the battery cell has a higher capacity.

[0122] In some embodiments, A satisfies: 2wt% ≤ A ≤ 20wt%. In this way, the battery cell can balance high conductivity and high capacity.

[0123] In some embodiments, based on the total mass of the composite material, the mass content B of the catalyst satisfies: 0.5wt% ≤ B ≤ 20wt%.

[0124] B can be 0.5wt%, 1wt%, 5wt%, 8wt%, 10wt%, 15wt%, 20wt% or any value within the above range.

[0125] When the mass content B of the catalyst is not less than 0.5 wt%, the contact area between the catalyst and the lithium-containing compound is appropriate, and it has a good catalytic effect, thus being beneficial to catalyze the decomposition of the lithium-containing compound and beneficial to improving the capacity of the battery; when the mass content of the catalyst does not exceed 20 wt%, it is beneficial to add more lithium-containing compounds to the composite material and beneficial to improving the capacity of the battery.

[0126] In some embodiments, B satisfies: 0.5 wt% ≤ B ≤ 10 wt%. In this way, it is beneficial to balance the capacity of the battery and the decomposition voltage of the lithium-containing compound.

[0127] In some embodiments, the sphericity of the particles of the composite material is 0.9 to 1. For example, the sphericity is 0.9, 0.95, 1 or any value within the above range. In this way, the particles of the composite material have a spherical or near-spherical morphology.

[0128] The sphericity of the composite material can be measured in the following way. The sphericity is the ratio of the surface area of a sphere identical to the object to the surface area of the object.

[0129] [Preparation method of composite material]

[0130] Figure 1 It is a schematic diagram of the preparation method of the composite material according to an embodiment of the present application, and this method can be used to prepare the composite material in any of the above embodiments. Combining Figure 1 as shown, method 100 includes the following steps.

[0131] Step 110, adding a lithium source, a catalyst, a conductive agent, and a pore-forming agent into a solvent to obtain a slurry.

[0132] The lithium source can be the lithium-containing compound in the above embodiments, or lithium hydroxide, as long as it can dissolve in the solvent and provide lithium ions. The solvent can be deionized water. As an example, the lithium-containing compound is dissolved in deionized water, and then the conductive agent, the catalyst, and the pore-forming agent are added, and after stirring, a uniform slurry is obtained. In this way, it is convenient for the full contact between the lithium-containing compound and the catalyst, and it is also convenient for the full contact between the lithium-containing compound and the conductive agent.

[0133] The pore-forming agent can dissolve in the solvent and is convenient to be removed in the subsequent process. After the slurry is prepared and dried, the dried powder includes the pore-forming agent. It can be understood that the pore-forming agent occupies a certain space in the dried powder; then, the dried powder is processed to remove the pore-forming agent in the powder, and vacancies are generated at the original positions of the pore-forming agent after removal, thereby preparing a composite material with a porous structure.

[0134] After the composite material is prepared, the catalyst can catalyze the decomposition of the lithium-containing compound at a lower voltage, and the catalyst can be the catalyst mentioned in the above embodiments. The catalyst includes one or more of oxides of transition metals, carbides of transition metals, nitrides of transition metals, or phosphides of transition metals.

[0135] Step 120, perform a drying treatment on the slurry to obtain the dried powder.

[0136] As an example, after the lithium-containing compound, the catalyst, the conductive agent, and the pore-forming agent are mixed uniformly in deionized water, a slurry is obtained; by performing a drying treatment on the slurry, a solid powder formed by mixing the lithium-containing compound, the catalyst, the conductive agent, and the pore-forming agent together can be obtained.

[0137] In the dried powder, there are secondary particles formed by the aggregation of the lithium-containing compound, the catalyst, the conductive agent, and the pore-forming agent.

[0138] The drying treatment can be a treatment step carried out at a certain temperature, that is, drying while heating. For example, the drying treatment is carried out at a temperature of 150°C to 250°C.

[0139] Step 130, perform a washing treatment on the dried powder to obtain the composite material.

[0140] Performing a washing treatment on the dried powder can remove the pore-forming agent in the dried powder.

[0141] As an example, place the dried powder in an anhydrous ethanol solvent, stir, wash, filter by suction, and dry to obtain the composite material. After the washing treatment, the pore-forming agent in the powder can be removed, and then after filtration by suction and drying, the composite material can be obtained.

[0142] The pore-forming agent can be dissolved in both deionized water and anhydrous ethanol. In this way, during the preparation of the slurry, it is convenient to dissolve the pore-forming agent in deionized water to facilitate the preparation of a slurry in which the pore-forming agent, the lithium-containing compound, the catalyst, and the conductive agent are mixed uniformly; and during the subsequent washing process, the pore-forming agent is dissolved in anhydrous ethanol, so that the pore-forming agent can be removed by anhydrous ethanol.

[0143] For the description of the lithium-containing compound, the catalyst, and the conductive agent, reference can be made to the description in the embodiments of the positive electrode active material, which will not be elaborated here.

[0144] In the embodiments of the present application, the composite material prepared by method 100 has good performance, which is beneficial to improving the capacity of the battery body; and this method is simple to operate and convenient for the preparation of the composite material.

[0145] In some embodiments, the pore-forming agent includes one or more of oxalic acid, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, or polyacrylic acid. The above-mentioned pore-forming agent is easily soluble in water and absolute ethanol. By selecting the above-mentioned pore-forming agent, it is convenient to prepare the composite material.

[0146] In some embodiments, the slurry is dried to obtain the dried powder, including: drying the slurry by spray drying to obtain the dried powder. By selecting the spray drying method, the drying is relatively rapid, and the slurry can be directly dried into powder.

[0147] As an example, a corresponding device is used for spray drying treatment. For example, the slurry enters the device through the feed port at a certain feed rate, and the temperature of the device for drying treatment is set to perform spray drying treatment on the slurry.

[0148] In some embodiments, the feed rate V of the slurry satisfies: 20 mL / min ≤ V ≤ 100 mL / min.

[0149] V can be 20 mL / min, 50 mL / min, 80 mL / min, 100 mL / min, or any value within the above range.

[0150] The feed rate of the slurry affects the size of the primary particles. By selecting the feed rate within the above range, it is beneficial to obtain primary particles of lithium-containing compounds with a more appropriate particle size.

[0151] Optionally, 45 mL / min ≤ V ≤ 85 mL / min. In this way, it is convenient to obtain primary particles of lithium-containing compounds with a more appropriate particle size.

[0152] In some embodiments, the temperature T of the drying treatment satisfies: 150 °C ≤ T ≤ 250 °C.

[0153] During the process of using the device for spray drying treatment, at the outlet of the device, hot air at a certain temperature is set to dry the slurry. Among them, the temperature of the drying treatment in this embodiment can be the temperature of the hot air.

[0154] T can be 150 °C, 200 °C, 250 °C, or any value within the above range.

[0155] The temperature of the drying treatment affects the growth and nucleation process of the secondary particles of the composite material. By selecting the temperature within the above range, it is beneficial to obtain secondary particles of the composite material with a suitable particle size.

[0156] Optionally, 175 °C ≤ T ≤ 225 °C. By selecting the temperature of the drying treatment within the above range, it is convenient to obtain secondary particles of the composite material with a more appropriate particle size.

[0157] In some embodiments, based on the sum of the masses of the lithium source, the catalyst, the conductive agent, and the pore-forming agent, the mass content C of the pore-forming agent satisfies: 1 wt% ≤ C ≤ 5 wt%; optionally, 2 wt% ≤ C ≤ 4 wt%.

[0158] C can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or any value within the above range.

[0159] As an example, the lithium source is lithium oxalate, and the mass content of the pore-forming agent is set based on the sum of the masses of lithium oxalate, the catalyst, the conductive agent, and the pore-forming agent.

[0160] The mass content of the pore-forming agent affects the specific surface area of the composite material. By selecting the mass content within the above range, it is beneficial to obtain a composite material with a suitable specific surface area.

[0161] It should be noted that in the embodiments of the present application, other parameters such as the feeding rate and the temperature of the drying treatment can also be set according to actual needs. The embodiments of the present application include but are not limited to this.

[0162] In some embodiments, the lithium source includes one or more of Li2C2O4, Li2CO3, Li2C4O4, Li2C3O5, Li2C4O6, or LiOH. The lithium source can be dissolved in a solvent and can provide lithium ions, so that a slurry containing lithium ions can be obtained, which is convenient for preparing a composite material through the slurry.

[0163] In some embodiments, the pore-forming agent in the dried powder is removed by washing treatment to obtain a composite material, including: adding the dried powder into absolute ethanol, and removing the pore-forming agent by washing and filtering to obtain a composite material. The pore-forming agent can be dissolved in absolute ethanol. By washing and filtering the dried powder with absolute ethanol, the pore-forming agent in the dried powder can be removed; after drying, a composite material with a porous structure and a large specific surface area can be obtained.

[0164] [Positive electrode plate]

[0165] The embodiments of the present application provide a positive electrode plate, including the composite material of any one of the above embodiments, and / or the composite material prepared by the method of any one of the above embodiments.

[0166] In some embodiments, the positive electrode plate further includes a positive electrode active material. The positive electrode active material can be a positive electrode active material known in the art for batteries. For example, the positive electrode active material is lithium iron phosphate, a ternary material, a lithium-rich manganese-based material, etc.

[0167] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector.

[0168] The positive current collector can be a metal foil or a composite current collector. For example, the positive current collector can be an aluminum foil.

[0169] The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0170] The positive electrode film layer may include a positive electrode active material and a composite material, and the composite material can be used as a lithium supplement agent.

[0171] The positive electrode film layer may also optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride - tetrafluoroethylene - propylene terpolymer, vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene terpolymer, tetrafluoroethylene - hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0172] The positive electrode film layer may also optionally include a conductive material. The conductive material may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0173] [Negative electrode tab]

[0174] The negative electrode tab includes a negative current collector and a negative electrode film layer disposed on the negative current collector.

[0175] The negative current collector can be a metal foil or a composite current collector. The negative current collector can be a copper foil. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0176] The negative electrode film layer includes a negative electrode active material. The negative electrode active material can be a negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material can include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can include one or more of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0177] The negative electrode film layer may also optionally include a conductive material. The conductive material can include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0178] [Electrolyte]

[0179] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. There is no specific limitation on the type of electrolyte in the embodiments of this application, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid.

[0180] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0181] The electrolyte salt can include one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium difluoro bis(oxalate) phosphate, and lithium tetrafluorooxalate phosphate.

[0182] The solvent can include one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0183] The electrolyte may also optionally include a negative electrode film-forming additive, a positive electrode film-forming additive, and may also include performance additives that can improve certain battery performances, such as performance additives for improving battery overcharge performance, improving battery high-temperature or low-temperature performance, etc.

[0184] [Separator]

[0185] The separator is used to separate the positive electrode plate and the negative electrode plate. There is no particular limitation on the type of the separator in the embodiments of the present application, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0186] The material of the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0187] The positive electrode plate, the negative electrode plate, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0188] [Secondary battery]

[0189] The embodiments of the present application provide a secondary battery, including the positive electrode plate in the above embodiments.

[0190] In some embodiments, the secondary battery is a secondary battery before formation. Formation can be understood as the initialization of the secondary battery, the process of activating the active substances of the secondary battery; it can also be understood as a process of charging the secondary battery.

[0191] The secondary battery in the embodiments of the present application can be a battery cell, and the battery cell can be a battery cell that has not been charged and discharged. For example, the battery cell is a newly assembled battery cell that has not been used. For example, the battery cell is a battery cell that has not undergone the formation process.

[0192] After the battery cell is assembled and used for a period of time, in the electrode plates of the battery cell, the lithium-containing compound in the composite material decomposes, and only a small amount or no lithium-containing compound exists in the electrode plates; the mass of the catalyst in the composite material basically does not change.

[0193] There is no particular limitation on the shape of the battery cell in the embodiments of the present application, and it can be cylindrical, square, or any other shape. The battery cell can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0194] Figure 2 It is a schematic diagram of a battery cell according to an embodiment of the present application. For example, as Figure 2 shown, the battery cell 3 is a square battery cell. The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0195] The electrode assembly 33 can be made of a positive electrode plate, a negative electrode plate, and a separator through a winding process or a stacking process.

[0196] The end cap assembly 32 includes electrode terminals 322. For example, asFigure 2 As shown, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0197] The battery cell 3 further includes a current collecting member 34 for connecting the tab 331 of the electrode assembly 33 and the electrode terminal 322. For example, when the electrode sheet 1 in the embodiment of the present application is a positive electrode sheet, one current collecting member 34 is used to connect the positive tab and the positive electrode terminal, and the other current collecting member 34 is used to connect the negative tab and the negative electrode terminal.

[0198] In some embodiments, the battery cells can be assembled into a battery module. The number of battery cells included in the battery module can be one or more, and those skilled in the art can select the specific number according to the application and capacity of the battery module.

[0199] [Battery]

[0200] The embodiment of the present application provides a battery including the battery cell in the above embodiment. Figure 3 It is a schematic diagram of the battery according to an embodiment of the present application. As Figure 3 shown, the battery 5 can include a plurality of battery cells (not shown in the figure).

[0201] The battery cells 3 can directly form the battery 5, or can first form a battery module, and then a plurality of battery modules form the battery 5.

[0202] [Electric device]

[0203] The embodiment of the present application provides an electric device including the battery described in the above embodiment.

[0204] Figure 4 It is a schematic diagram of the electric device according to an embodiment of the present application. As Figure 4 shown, the present application provides an electric device 6 including the battery in the above embodiment.

[0205] Optionally, the electric device can also be an energy storage device, a lighting device, a spacecraft, etc., and the embodiments of the present application include but are not limited to this.

[0206] Hereinafter, the embodiments of the present application will be described. The following described embodiments are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those not specified in the embodiments in terms of specific technology or conditions, they shall be carried out according to the technology or conditions described in the literature in the field or according to the product specifications. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0207] [Embodiment]

[0208] Embodiment 1

[0209] In Example 1, the composite material comprises a lithium-containing compound, a catalyst, and a conductive agent. Among them, the lithium-containing compound is Li2C2O4, the catalyst is NiO, and the conductive agent is Ketjen black. In the composite material, based on the total mass of the composite material, the mass content A of the conductive agent (carbon material) is 10 wt%, and the mass content B of the catalyst (NiO) is 5 wt%. The volume average particle size Dv502 of the secondary particles of the composite material is 5 μm, and the volume average particle size Dv501 of the primary particles of the lithium-containing compound is 200 nm. The specific surface area S of the composite material is 70 m 2 / g, and the powder resistivity R of the composite material is 0.512 Ω·cm.

[0210] In the process of preparing the composite material of Example 1, the pore-forming agent added is H2C2O4. Based on the total mass of the pore-forming agent, the lithium-containing compound, the catalyst, and the conductive agent, the mass content C of the pore-forming agent is 3 wt%. During the spray drying process, the drying temperature T is 200 °C, and the feeding rate V is 70 mL / min.

[0211] Examples 2-5

[0212] The differences between Examples 2-5 and Example 1 are as follows: the mass content A of the conductive agent is different.

[0213] Examples 6-9

[0214] The differences between Examples 6-9 and Example 1 are as follows: the mass content B of the catalyst is different.

[0215] Examples 10-13

[0216] The differences between Examples 10-13 and Example 1 are as follows: the feeding rate V is different. Correspondingly, the volume average particle size Dv501 of the primary particles of the lithium-containing compound is different.

[0217] Examples 14-17

[0218] The differences between Examples 14-17 and Example 1 are as follows: the drying temperature T is different. Correspondingly, the volume average particle size Dv502 of the secondary particles of the composite material is different.

[0219] Examples 18-21

[0220] The differences between Examples 18-21 and Example 1 are as follows: the mass content C of the pore-forming agent is different. Correspondingly, the specific surface area S, the total pore volume V, and the average pore diameter D of the composite material are different.

[0221] Examples 22-24

[0222] The differences between Examples 22-24 and Example 1 are as follows: the types of the lithium-containing compound are different.

[0223] Examples 25 - 29

[0224] The difference between Examples 25 - 29 and Example 1 lies in: different types of catalysts.

[0225] Example 30

[0226] The difference between Example 30 and Example 1 lies in: lithium iron phosphate is additionally added as the positive electrode active material to prepare a battery monomer. Based on the total mass of lithium iron phosphate and the composite material, the mass content of the composite material is 5 wt%, and the mass content of lithium iron phosphate is 95 wt%.

[0227] Comparative Example 1

[0228] The difference between Comparative Example 1 and Example 1 lies in: its material is not a composite material, but only a lithium-containing compound.

[0229] Comparative Example 2

[0230] The difference between Comparative Example 2 and Example 1 lies in: its material is a material after mixing a lithium-containing compound and a catalyst, without a conductive agent.

[0231] Comparative Example 3

[0232] The difference between Comparative Example 3 and Example 1 lies in: its material is a material after mixing a lithium-containing compound and a conductive agent, without a catalyst.

[0233] Comparative Example 4

[0234] The difference between Comparative Example 4 and Example 1 lies in: no pore-forming agent was added during the preparation of its material, and its material is relatively dense.

[0235] Comparative Example 5

[0236] The difference between Comparative Example 5 and Comparative Example 4 lies in: lithium iron phosphate is additionally added as the positive electrode active material to prepare a battery monomer. Based on the total mass of lithium iron phosphate and the composite material, the mass content of the composite material is 5 wt%, and the mass content of lithium iron phosphate is 95 wt%.

[0237] In Comparative Examples 1 - 4, the provided materials were not added with a pore-forming agent during the preparation process, but were obtained by preparing the corresponding raw materials into a slurry and performing spray drying treatment. In addition, it should be noted that in Comparative Example 1, the selected material is a pure lithium-containing compound. Although it has undergone spray drying treatment, it is difficult to prepare the lithium-containing compound into a spherical shape through the spray drying treatment method.

[0238] As shown in Table 1 and Table 2, in Examples 1-29 and Comparative Examples 1-4, lithium-ion battery monomers were prepared using a composite material as the cathode active material. As shown in Table 3, in Example 30 and Comparative Example 5, a composite material was used as the lithium supplement agent and lithium iron phosphate was used as the cathode active material to prepare lithium-ion battery monomers.

[0239] In Table 1, V is the total pore volume of the composite material, D is the average pore diameter of the composite material, A is the mass content of the conductive agent, B is the mass content of the catalyst, Dv501 is the volume average particle size of the lithium-containing compound of the primary particles, Dv502 is the volume average particle size of the composite material of the secondary particles, S is the specific surface area of the composite material, and R is the powder resistivity of the composite material.

[0240] Table 1 Parameters of the composite materials in Examples 1-19 and Comparative Examples 1-4

[0241]

[0242]

[0243] It should be noted that in Table 1, the total pore volume in Comparative Examples 2-4 is less than 0.005 cm 3 / g, and this value is close to 0. In some detection instruments, the displayed value may be 0, and in some high-precision detection instruments, the displayed value is basically less than 0.005 cm 3 / g. In Comparative Examples 2-4, since the total pore volume is less than 0.005 cm 3 / g, it can be considered that there are basically no pores, and thus the average pore diameter of the materials corresponding to Comparative Examples 2-4 is not shown in the table.

[0244] Table 2 Parameters of the preparation methods of the composite materials in Examples 10-21

[0245]

[0246] Table 3 Experimental results of Examples 1-29 and Comparative Examples 1-4

[0247]

[0248]

[0249] Table 4 Experimental results of Example 30 and Comparative Example 5

[0250]

[0251] [Preparation of battery monomers in Examples 1-29 and Comparative Examples 1-4]

[0252] (1) Preparation of the positive electrode sheet: The composite material, binder polyvinylidene fluoride (PVDF), and conductive agent (acetylene black) are dissolved in the solvent N-methylpyrrolidone (NMP) according to a mass ratio of 97:2:1, and after being fully stirred and mixed evenly, a positive electrode paste is prepared; the positive electrode paste is evenly coated on the positive electrode current collector aluminum foil, and then through drying, cold pressing, and slitting, the positive electrode sheet is obtained. In the preparation of this positive electrode sheet, no other active materials are added.

[0253] (2) Preparation of the negative electrode sheet: The negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water according to a mass ratio of 96:1.5:1.5:1.0, and after being fully stirred and mixed evenly, a negative electrode paste is prepared; the negative electrode paste is coated on the negative electrode current collector copper foil, and then through drying, cold pressing, and slitting, the negative electrode sheet is obtained.

[0254] (3) Separator: A polypropylene film is used.

[0255] (4) Preparation of the electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed according to a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain the electrolyte. In this electrolyte, the concentration of LiPF6 is 1 mol / L.

[0256] (5) Preparation of the lithium-ion battery monomer: The above positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer package, the above-prepared electrolyte is added, and after processes such as encapsulation, standing, formation, and aging, the lithium-ion battery monomer is obtained.

[0257] [Preparation of the battery monomers of Example 30 and Comparative Example 5]

[0258] (1) Preparation of the positive electrode sheet: The composite material and the positive electrode active material lithium iron phosphate (LFP), binder polyvinylidene fluoride (PVDF), and conductive agent (acetylene black) are dissolved in the solvent N-methylpyrrolidone (NMP) according to a mass ratio of 97:2:1, and after being fully stirred and mixed evenly, a positive electrode paste is prepared; the positive electrode paste is evenly coated on the positive electrode current collector aluminum foil, and then through drying, cold pressing, and slitting, the positive electrode sheet is obtained. In the preparation of this positive electrode sheet, the composite material is used as a lithium supplement agent.

[0259] (2) Preparation of the negative electrode sheet: The artificial graphite as the negative electrode active material, acetylene black as the conductive agent, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC-Na) as the thickener are dissolved in deionized water according to a mass ratio of 96:1.5:1.5:1.0, and after being fully stirred and mixed evenly, a negative electrode slurry is prepared; the negative electrode slurry is coated on the negative electrode current collector copper foil, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0260] (3) Separator: A polypropylene film is used.

[0261] (4) Preparation of the electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain the electrolyte. In this electrolyte, the concentration of LiPF6 is 1 mol / L.

[0262] (5) Preparation of the lithium-ion battery: The above positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer package, the prepared electrolyte is added, and after processes such as encapsulation, standing, formation, and aging, a lithium-ion battery monomer is obtained.

[0263] [Measurement of the first-cycle charging capacity]

[0264] The assembled lithium-ion battery is charged at a constant current of 0.1C to 4.25V, left standing for 5 min, and the first-cycle charging capacity of the lithium-ion battery at this time is recorded; the first-cycle charging capacity of the lithium-ion battery is obtained by dividing the first-cycle charging capacity of the battery by the mass of the corresponding active material.

[0265] In Examples 1-29, the mass of the corresponding active material is the mass of the composite material; in Comparative Examples 1-4, the mass of the corresponding active material is the mass of the active material selected in the comparative example. The specific active material can be seen in the above description and will not be elaborated here. For Example 30 and Comparative Example 5, the mass of the corresponding active material also includes the mass of lithium iron phosphate.

[0266] [Measurement of the average volume particle size]

[0267] The average volume particle size can be determined by a particle size analyzer - laser diffraction method. Specifically, reference can be made to Standard GB / T19077-2016, and a laser diffraction scattering particle size analyzer can be used to measure according to the manufacturer's instructions. For example, an appropriate amount of lithium-containing compound is taken before preparing the composite material (or an appropriate amount of the composite material is taken after the composite material is prepared), and a Malvern 2000 (MasterSizer 2000) laser particle size analyzer is used to test the average volume particle size of the material. For example, an appropriate amount of the sample to be tested (the sample concentration ensures a light obscuration of 8-12%) is taken, 20 ml of deionized water is added, and at the same time, it is ultrasonically treated for 5 min (53 KHz / 120 W) to ensure that the sample is completely dispersed, and then the sample is measured according to the standard of GB / T19077-2016 / ISO 13320:2009.

[0268] [Measurement of the powder resistivity of the composite material]

[0269] The powder of the composite material is dried, an appropriate amount of the powder is weighed, and then a powder resistivity tester (ST2722 digital four-probe instrument, manufactured by Suzhou Jingge Electronics Co., Ltd.) is used to measure the powder resistivity of the sample according to GB / T 30835-2014, and the test pressure is 20 MPa.

[0270] [Measurement of the decomposition voltage]

[0271] The decomposition voltage of the lithium-containing compound is the average charging voltage during the first charging process, that is, the ratio of the charging energy to the charging capacity. The charging energy and the charging capacity can be obtained by a test device connected to the lithium-ion battery.

[0272] [Measurement of the specific surface area, total pore volume, and average pore diameter]

[0273] The BET specific surface area has a well-known meaning in the art and can be measured by well-known instruments and methods in the art. For example, the specific surface area is measured by the gas adsorption method and tested according to the test standard of GB / T19587 2017. Specifically as follows: The composite material is taken as the sample, the sample tube is immersed in liquid nitrogen at -196 °C, and the adsorption amount of nitrogen on the solid surface at different pressures is measured under a relative pressure of 0.05-0.30. Based on the BET multi-layer adsorption theory and its formula, the monolayer adsorption amount of the sample is obtained, and thus the specific surface area of the composite material is calculated. At the same time, the total pore volume and the average pore diameter of the composite material can also be measured.

[0274] [Measurement of the mass content of the conductive agent, the mass content of the catalyst, and the mass content of the lithium-containing compound in the composite material]

[0275] The components of the composite material and the mass content of each component can be measured by the following method.

[0276] As an example, an appropriate amount of the composite material powder is taken, and the elemental composition in the composite material is determined by an energy spectrometer. Then, the material and mass content of each component are measured by thermogravimetric analysis.

[0277] As an example, an appropriate amount of the composite material powder is taken, and the powder is dissolved in deionized water (or a corresponding soluble solvent). Since the lithium-containing compound can be dissolved in water, the lithium-containing compound can be separated from the composite material, the weight of the lithium-containing compound is measured, and then the mass content of the lithium-containing compound is calculated. Then, the undissolved substance in the powder is added to another solvent that can dissolve the catalyst, the weight of the catalyst is measured, and the mass content of the catalyst is calculated. Finally, a substance containing only the conductive agent can be obtained, and the mass content of the conductive agent can be obtained by weighing.

[0278] It should be noted that the initial charge capacity, average volume particle size, resistivity, decomposition voltage, specific surface area, mass content of the conductive agent in the composite material, mass content of the catalyst, and mass content of the lithium-containing compound in the embodiments of the present application are common knowledge in the art, have the meanings well-known in the art, and can be measured by the well-known test methods and instruments in the art.

[0279] In the embodiments of the present application, the capacity of the battery is reflected by the initial charge capacity of the battery cell.

[0280] Figure 5 is the SEM schematic diagram of the composite material of an embodiment of the present application, Figure 6 is the enlarged SEM schematic diagram of a part of the composite material of an embodiment of the present application; Figure 7 is the EDS schematic diagram of the composite material of an embodiment of the present application. Figure 8 is the SEM schematic diagram of the composite material of a comparative example of the present application, Figure 9 is the enlarged SEM schematic diagram of a part of the composite material of a comparative example of the present application.

[0281] Combined with Figure 5 as shown, the morphology of the composite material in the embodiments of the present application is secondary particles, and the composite material is spherical or close to spherical in shape. Combined with Figure 5 and Figure 6 as shown, the composite material has multiple pores and channels, is a material with a porous structure, and the composite material is relatively loose. Combined with Figure 6 as shown, multiple primary particle lithium-containing compounds and multiple conductive agent particles (carbon materials) can also be seen, and the lithium-containing compound particles and the conductive agent particles are in contact. In addition, Figure 7 shows the distribution of each element in the composite material. Specifically, the distribution of the Ni element in the catalyst and the C element in the lithium-containing compound can be seen, and the distribution of the Ni element in the catalyst is in contact with the C element in the lithium-containing compound. Combined withFigure 7 and Figure 8 As shown, the composite material of the comparative example is denser than that of the example.

[0282] Combined with Examples 1-29 and Comparative Examples 1-4, the composite material of the embodiments of the present application can improve the first-cycle charging capacity of the battery cell.

[0283] Combined with Comparative Example 2, only by mixing a lithium-containing compound and a catalyst, the mixed material has a high resistivity, and the adverse effects caused by the vacancies generated after the decomposition of the lithium-containing compound cannot be solved, and the capacity of the battery is low.

[0284] Combined with Comparative Example 3, only by mixing carbon and a lithium-containing compound, the decomposition voltage of the lithium-containing compound is high, which is not conducive to improving the capacity of the battery. Although in Comparative Example 3, only by mixing carbon and a lithium-containing compound, the resistivity of the powder is reduced, but due to the high decomposition voltage of the lithium-containing compound, it is difficult to be used normally.

[0285] Combined with Comparative Example 4, in the process of preparing the composite material, no pore-forming agent is added, the prepared composite material is denser, the specific surface area of the composite material is lower, and the capacity of the battery is lower.

[0286] In the composite materials of Comparative Examples 1-4, no pore-forming agent was added during the preparation process of the composite materials. Therefore, the prepared composite materials are solid structures, and the total pore volume and average pore diameter are recorded as 0.

[0287] Combined with Examples 1-5, when the mass content of the carbon material is set to 1 wt% to 40 wt%, the battery cell has a high capacity and the composite material has a low powder film resistivity; when the mass content of the carbon material is set to 2 wt% to 20 wt%, the composite material has a lower powder resistivity while the battery cell has a higher capacity.

[0288] Combined with Examples 6-9, when the mass content of the catalyst is set to 0.5 wt% to 20 wt%, the battery cell has a high capacity and a low decomposition voltage; when the mass content of the catalyst is set to 1 wt% to 10 wt%, the lithium-containing compound has a low decomposition voltage, and at the same time the battery cell has a higher capacity.

[0289] The total pore volume and average pore diameter of the composite material have slight fluctuations with the changes in the mass content of the carbon material and the mass content of the catalyst, but the changes are small.

[0290] As shown in Examples 10 - 13, the size of the primary particles of the lithium-containing compound is related to the temperature of the drying treatment. When the feeding rate is set within the range of 20 mL / min to 100 mL / min, the volume average particle size Dv501 of the primary particles of the lithium-containing compound is within 50 nm to 500 nm. Further, when the feeding rate is set within the range of 45 mL / min to 85 mL / min, the volume average particle size Dv501 of the primary particles of the lithium-containing compound is within 100 nm to 300 nm, which can further balance the decomposition voltage of the lithium-containing compound and the capacity of the battery.

[0291] As shown in Examples 14 - 17, the size of the secondary particles of the composite material is related to the feeding rate. When the temperature of the drying treatment is within the range of 150 °C to 250 °C, the volume average particle size Dv502 of the secondary particles of the composite material is within 1 μm to 15 μm. Further, when the temperature of the drying treatment is within the range of 175 °C to 225 °C, the volume average particle size Dv502 of the secondary particles of the composite material is within 1 μm to 10 μm, and the battery cell has a higher capacity.

[0292] As shown in Examples 18 - 21, the specific surface area of the composite material is related to the mass content of the pore-forming agent added during the preparation of the composite material. When the mass content of the pore-forming agent is within the range of 1 wt% to 5 wt%, the specific surface area of the composite material is within 10 m 2 / g to 150 m 2 / g, the total pore volume of the composite material is within 0.02 cm 3 / g to 1 cm 3 / g, and the average pore diameter is within the range of 2 nm to 50 nm. Further, when the mass content of the pore-forming agent is within the range of 2 wt% to 4 wt%, the total pore volume of the composite material is within 0.1 cm 3 / g to 0.5 cm 3 / g, the average pore diameter is within the range of 5 nm to 20 nm, and when the specific surface area of the composite material is within the range of 30 m 2 / g to 100 m 2 / g, the battery cell has a higher capacity.

[0293] As shown in Examples 22 - 24, the embodiments of the present application are applicable to a variety of different lithium-containing compounds; as shown in Examples 25 - 29, the embodiments of the present application are applicable to a variety of different catalysts.

[0294] As shown in Example 30 and Comparative Example 5, after the composite material of the embodiments of the present application and the cathode active material lithium iron phosphate are mixed, the prepared battery cell has a higher capacity.

[0295] Although only lithium iron phosphate is shown as the positive electrode active material in the embodiments, the composite material of the present application is also applicable to battery monomers with other active materials.

[0296] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same composition and the same effect as the technical idea within the technical solution scope of the present application are all included in the technical scope of the present application. In addition, within the scope of not departing from the gist of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A composite material, characterized in that, Comprising: a lithium-containing compound, a catalyst and a conductive agent, wherein, the lithium-containing compound comprises lithium element, carbon element and oxygen element; the catalyst comprises one or more of transition metal oxides, transition metal carbides, transition metal nitrides or transition metal phosphides; The total pore volume V of the composite material satisfies: 0.02 cm 3 / g ≤ V ≤ 1 cm 3 / g, and the average pore diameter D of the composite material satisfies: 2 nm ≤ D ≤ 50 nm.

2. The composite material according to claim 1, characterized in that, The total pore volume V of the composite material satisfies: 0.1 cm 3 / g ≤ V ≤ 0.5 cm 3 / g, and the average pore diameter D of the composite material satisfies: 5 nm ≤ V ≤ 20 nm.

3. The composite material according to claim 1 or 2, characterized in that, the morphology of the lithium-containing compound is primary particles, and / or the morphology of the composite material is secondary particles.

4. The composite material according to any one of claims 1 to 3, characterized in that, The specific surface area S of the composite material satisfies: 10 m 2 / g ≤ S ≤ 150 m 2 / g; optionally, 30 m 2 / g ≤ S ≤ 100 m 2 / g.

5. The composite material according to any one of claims 1-4, characterized in that, The sphericity of the particles of the composite material is 0.9 - 1.

6. The composite material according to any one of claims 1-5, characterized in that, The chemical formula of the lithium-containing compound is Li2C x O y , where 1 ≤ x ≤ 4 and 3 ≤ y ≤ 6; optionally, the lithium-containing compound includes one or more of Li2C2O4, Li2CO3, Li2C4O4, Li2C3O5 or Li2C4O6.

7. The composite material according to any one of claims 1-6, characterized in that, The chemical formula of the oxide of the transition metal is M α O β , where 0 < α ≤ 3, 0 < β ≤ 5, and M includes one or more of Ni, Co, Fe, Mn, V, Cr, Cu, or Ti; Optionally, M α O β comprises one or more of NiO, Co3O4, Fe2O3, MoO3 or V2O5.

8. The composite material according to any one of claims 1-7, characterized in that, The transition metal carbides include one or more of molybdenum carbide, vanadium carbide, tungsten carbide, titanium carbide, cobalt carbide, iron carbide or nickel carbide; and / or the transition metal nitrides include one or more of molybdenum nitride, vanadium nitride, titanium nitride, manganese nitride, cobalt nitride, iron nitride or nickel nitride; and / or the transition metal phosphides include one or more of nickel phosphide, cobalt phosphide, manganese phosphide, tungsten phosphide or molybdenum phosphide.

9. The composite material according to any one of claims 1-8, characterized in that, The conductive agent comprises carbon materials; optionally, the conductive agent comprises carbon-based conductive agents; optionally, the carbon materials include one or more of carbon nanotubes, carbon fibers, acetylene black, Ketjen black, conductive carbon black, C60 or graphene.

10. The composite material according to any one of claims 1-9, characterized in that, The volume average particle size Dv501 of the lithium-containing compound satisfies: 50 nm ≤ Dv501 ≤ 500 nm; optionally, 100 nm ≤ Dv501 ≤ 300 nm.

11. The composite material according to any one of claims 1-10, characterized in that, The volume average particle size Dv502 of the composite material satisfies: 1 μm ≤ Dv502 ≤ 15 μm; optionally, 2 μm ≤ Dv502 ≤ 10 μm.

12. The composite material according to any one of claims 1-11, characterized in that, Based on the total mass of the composite material, the mass content A of the conductive agent satisfies: 1 wt% ≤ A ≤ 40 wt%; optionally, A satisfies: 2 wt% ≤ A ≤ 20 wt%.

13. The composite material according to any one of claims 1 to 12, characterized in that, Based on the total mass of the composite material, the mass content B of the catalyst satisfies: 0.5 wt% ≤ B ≤ 20 wt%; optionally, B satisfies: 1 wt% ≤ B ≤ 10 wt%.

14. A method for preparing a composite material, characterized in that, Comprising: Adding a lithium source, a catalyst, a conductive agent and a pore-forming agent into a solvent to obtain a slurry, wherein the catalyst comprises one or more of transition metal oxides, transition metal carbides, transition metal nitrides or transition metal phosphides; Performing a drying treatment on the slurry to obtain a dried powder; Performing a washing treatment on the dried powder to obtain the composite material.

15. The preparation method according to claim 14, wherein, The pore-forming agent includes one or more of oxalic acid, polyethylene glycol, polyethylene oxide, polyvinyl alcohol or polyacrylic acid.

16. The preparation method according to claim 14 or 15, characterized in that, The performing a drying treatment on the slurry to obtain a dried powder includes: Performing a drying treatment on the slurry by spray drying to obtain a dried powder.

17. The preparation method according to claim 16, wherein During the drying treatment, the feeding rate V of the slurry satisfies: 20 mL / min ≤ V ≤ 100 mL / min; optionally, 45 mL / min ≤ V ≤ 85 mL / min.

18. The preparation method according to claim 16 or 17, characterized in that, The temperature T of the drying treatment satisfies: 150 °C ≤ T ≤ 250 °C; optionally, 175 °C ≤ T ≤ 225 °C.

19. The preparation method according to any one of claims 14-18, characterized in that, Based on the sum of the masses of the lithium source, the catalyst, the conductive agent, and the pore-forming agent, the mass content C of the pore-forming agent satisfies: 1 wt% ≤ C ≤ 5 wt%; optionally, 2 wt% ≤ C ≤ 4 wt%.

20. The preparation method according to any one of claims 14-19, characterized in that, The lithium source includes one or more of Li2C2O4, Li2CO3, Li2C4O4, Li2C3O5, Li2C4O6, or LiOH.

21. The preparation method according to any one of claims 14-20, characterized in that, The removing of the pore-forming agent from the dried powder through washing treatment to obtain the composite material includes: Adding the dried powder into absolute ethanol, and removing the pore-forming agent through washing and filtration to obtain the composite material.

22. A positive electrode plate, characterized in that, Includes: The composite material according to any one of claims 1-13, and / or, the composite material obtained by the preparation method according to any one of claims 14-21.

23. A secondary battery, characterized in that, Includes the positive electrode sheet as claimed in claim 22.

24. The secondary battery according to claim 23, wherein The secondary battery is a secondary battery before formation.

25. An electrical device, characterized in that, Includes the secondary battery as claimed in claim 23 or 24.

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